Hydraulic control system



y 7, 1959 R. E. BAUER 2,893,355 v HYDRAULIC CONTROL SYSTEM 1 Filed Jan. 12, 1953 I 5 Sheets-Sheet 1 INVENTOR. lb 71155622225411. E B

rail/5Y5.

R. E. BAUER HYDRAULIC CONTROL SYSTEM July 7, 1959 5 Sheets-Sheet 2 Filed Jan. 12, 1953 WM Q m. r 2 K F y 7, 1959 R. BAUER 2,893,355

I HYDRAULIC CONTROL SYSTEM Filed .Jan. 12, 1953 I 5 s -s 3 INVENTOR. Fussa-ZZ ZTZaztcr:

July. 7 1959 R. E. BAUER 2,393,355

HYDRAULIC comm. SYSTEM Filed Jan. 12, 1953 v 5 Sheets-She et 4 IN V EN TOR. F22 .919 62/2? ,Zazze/f M Y/IZMQ ralmf July 7, 1959 f R; E. BAUER HYDRAULIC CONTROL SYSTEM Filed Jan. 12, 1953 5 Sheets-Sheet 5 INVENTOR.

WFNE)$.

77:15.5:ZZ 27,54 :1 en

.llIl.

States Patent isaasss iiYiSiiAI'JLIC CONTROL SYSTEM RussellE. liau'er, Grosse Ptiinte Woods, Mich, assignbr to Gadi llacGage Company, Roseville, Mich, a corporation of Michigan Application Januar 12, 1953, Serial No. 330,871 3 Claims. 01. 121-39 'Ihis'inve'ntion relates generally to hydraulic control systems and more particularly to apparatus for aiming the cannon of a' combat vehicle.

An object of this invention is to provide an improved control system for controlling elevation and rotation of a device such as a cannon.

Another object is to provide a system of this nature which is extremely compact and which is simple and eflicient in its operation.

Another object of this invention is to provide such an apparatus in which there are a minimum of parts interconnected by conduits which might be ruptured during combat.

Another object of this invention is to provide such an apparatus which may be manually operated in the event of damage to the power system.

Another object of this invention is to provide such an apparatus that the drain on the electric power supply will be low when in operation and will be nil when in standby operation.

Another object of this invention is to provide such an apparatus that will be silent in operation to minimize the chance of detection by the enemy when the vehicle on which it is installed is in ambush.

Another object of this invention is to provide such an apparatus in which there is a minimum of lag between operation of the controls and actual movement of the cannon.

Another object of this invention is to provide such an apparatus which will permit very accurate tracking of targets.

Another object of this invention is to provide such an apparatus which will permit rapid and accurate laying of cannon on fixed targets.

Other objects of this invention will be apparent from the description and the drawings, in which drawings:

Fig. 1 is adiagrammatic representation of one form of the controlling apparatus embodying the invention;

Fig. 1A is an enlarged view of one of the spool valves shown in Fig. 1;

Fig. 2 is a view in side elevation showing a commercial form of the apparatus;

Fig. 3 is a plan view of the apparatus of Fig. 2 showing the commanders override control attached thereto;

Fig. 4 is a modified form of a portion of the hydraulic control system shown in Fig. 1;

Fig. 5 is a plan view of the valve control box, the cover being removed, and the associated gunners control;

Fig. 6 is a partial view similar to Fig. 5 showing the valve control box in a position to respond to the commanders control;

Fig. 7 is a view taken substantially along the line 77 of Fig. 5;

Fig. 8 is a view taken substantially along the line 8-8 of Fig. 5;

Fig. 9 is a frontelevation view of a portion paratus shown in Figs. 6, 7 and 8;

of the ap- ."ice

Fig. 10 is a side elevational view of the apparatus shown in Fig. 9';

Fig. 11 is a side elevational view partly in section of the commanders override control;

Fig. 12 is a view of the commanders control handle with certain of the parts broken away to show the switch structures thereof; and, p I

Fig. 13 is an' end view of the commanders control with a portibn of the housing broken away.

Controls for, the aiming of a tank cannon have been heretofore designed and have been heretofore used but have been subject to certain disadvantages which my apparatus completely overcomes. For example, prioi art controls involve a complicated combination of electrical and hydraulic systems and therefore include a number of costly relays and other equipment which, while from many standards are fast operating, are not sufliciently fast when cannons are being aimed under combat conditions. For example, a very appreciable time lapse will occur between operation of the controls by the gunner and response thereto in the aiming of the cannon. Such delay, of course, is not desirable since under combat conditions it may mean the difference as to whether the enemy or the gunner is able to obtain the first crucial shot. The present invention provides a system for directing fire from tanks or other combat vehicles with extreme accuracy and speed and permits the accurate tracking of moving targets or laying on a fixed target.

Generically, the aiming is effected by manual operation of a pair of valves. which meter the flow of oil or other hydraulic fiuid to control the cannon elevating cylinder and the traversing motor for rotating the turret. The present embodiment is of durable but light construction and is small in over-all size which particularly adapts it to any of the light, medium or heavy tanks and gun motor carriages. The elimination of much intermediate control mechanism, such as feedbacks, dither devices, servo devices, electronic valves, accessory pumps, gyros, inverters, difierentials, etc., found in many of the prior art systems, not only reduces the time lags in the control system but also reduces the power consumption to a small fraction of that required by systems presently being used by the armed forces.

The hydraulic pressure fluid for operation of the trawersing motor and the elevating cylinder is obtained from a main power fluid accumulator tank which is periodically changed from a fluid reservoir and is of such size that normal tracking and laying on target can be conducted over long periods of time without the necessity of operating the main tank engine or auxiliary generator.

The system is further arranged so that the combat vehicle will not be put out of commission by the failure of any one conduit which might be ruptured during combat. In the event of the rupture of any line of the power system, the cannon may be aimed by the hand system and if any line of the hand system is ruptured, the cannon may still be aimed by power. The hydraulic fluid from one system cannot be lost through failure of any part of the other system. Further, all internal hydraulic fluid passages are drilled or manifolded in solid metal to lessen the chance of rupture during operation.

In the past, the thinking has been that hydraulic con trols based on a pressure metering system were impractical since the hydraulic motor actuated thereby would be jerky in operation, tending first to bind up and then to go at uncontrollable, speeds, and for that reason the more complicated variable displacement pumps were employed for controlling the volume of the hydraulic fluid in the motor. Also, past systems have required a variable displacement pump for traversing the cannon, and one for elevating the gun, as well as a system charging pump.

In accordance with this invention, however, the speed of operation of such fluid motor is controlled by metering the hydraulic fluid on both the inlet and the outlet or return sides of the fluid motor whereby sudden surges of pressure are eliminated, and smooth operation is achieved at all tracking speeds or times of laying on target regardless of variations in torque due to improperly fitted gears or tight and loose spots in the turret; Also, only one simple hydraulic pump is required.

Referring now to Figs. 1, 2, and 3 of the drawings wherein there is illustrated a preferred embodiment of the invention, 1 designates generally a hydraulically actuated combat vehicle cannon aiming apparatus comprising a vertically mounted electric motor 2, a hollow casing 3 mounted above the motor and providing a hydraulic fluid reservoir 11, within which a liquid pump 10 and filter 14 are enclosed. A valve block 4 is mounted above the casing 3 for controlling the admission of hydraulic fluid to a hydraulic motor 5 which rotates the cannon and to a cannon elevating cylinder 6. A valve control box 7, which may be controlled either from the gunners control mechanism '8 or the commanders control mechanism 9 is mounted adjacent to the valve block 4 for actuating a pair of spool valves 40 and 41 contained within the valve block 4.

The electric pump motor 2 drives the liquid pump 10 which may be a simple gear pump as shown. The pump 10 forces hydraulic fluid from the fluid reservoir 11 through a check valve 12 and filter 14, a vertically extending passageway 16, and a conduit 18 into the main hydraulic power accumulator 20 to provide a ready and steady source of high pressure hydraulic fluid of, for example, 1000 pounds p.s.i. for actuating the motor 5 and the cylinder 6. The accumulator 20 may be of any usual construction, and as herein shown comprises a sealed tank 22 containing an expansible-contractible gas filled bladder 24 which provides the required pressure above the liquid and serves to prevent intermingling of the pressure maintaining gases contained therein with the hydraulic liquid of the hydraulic system. A pressure actuated switch 26 normally controls the energizing circuit of the motor 2 to maintain the fluid pressure in the accumulator between predetermined pressure limits. The check valve 12 prevents back flow of hydraulic fluid into the reservoir 11 during standby periods of the pump 10. As a safety precaution a relief by-pass valve 28 is provided to by-pass at least some of the fluid pumped by the gear pump 10 in the event its discharge pressure becomes excessive.

The passageway 16 extends from its junction with the accumulator passageway 18 upwardly into the valve block 4, which is mounted on top of the unit rearwardly of the valve control box 7. As shown in Fig. 1, the valve block 4 is provided with a spool type master valve 32, which during normal operation is actuated to open position by an electric solenoid 34. The valve 32 is shown in its open, or energized position in which the passageway 16 is in open communication with the center sections 35 of the valve chambers 36 and 38. Spool type traverse and elevation controlling valves 40 and 41 are respectively positioned within the chambers 36 and 38. They are shown in their normal, or closed positions in which they act to prevent any passage of pressure fluid from the passageway 35 to either of the outlet ports 42-44 of chamber 36 or 43-45 of the chamber 38. The ports 42 and 44 control fluid supplied to passageways 46 and 47 and conduits 48 and 49 of the hydraulic traversing motor 5. The passageways 46 and 47 lead through a central section 50 of the chamber 51 housing the spool element 52 of the master valve 32. In the open position of the master valve 32 the passageways 46 and 47 are separated from each other by a land 53 of the element 52. In the de-energized, or closed position of the valve 32 the spool element 52 thereof moves to the right under the force'of a spring 54 whereby the land 53 moves to the right of the passageway 47, and a reduced diameter portion 55 of the element 52 which is intermediate the land 53 and a second land 56 interconnects these two passageways 46 and 47 to permit fluid from the motor to circulate freely during manual rotation of the turret- This is necessary since the motor 5 in present tank practice is continually connected through gearing (not shown) with the tank ring gear (not shown), and therefore ro tation of the turret is accompanied by rotation of the motor 5 which their acts as a pump. When the master valve 32 is closed, third land 57 of the element 52 closes the passageway 16 to prevent flow of high pressure fluid from the accumulator 20 to the four-way control valves 40 and 41.

The elevation controlling valve 41 in its closed, or centered position prevents passage of fluid from the passageway 35 to either of the outlet ports 43 or 45, which are connected by passageways 58 and 59 and conduits 60 and 61 respectively to the cannon elevating cylinder 6. The spool valves 40 and 41 are each normally held in their closed, or centered positions. Since each of the valves 40 and 41 is substantially identical, a detailed description of but one thereof is deemed to be suflicient to understand the construction of both and valve 41 will therefore be described. Valve 41 is provided with a pair of spaced lands 62 and 63 which are each provided with flattened tapered surfaces 64, 65, 66 and 67 (Fig. 1A), the taper of the surfaces 64 and 67 preferably being the same and the taper of the surfaces 65 and 66 being the same. In many instances the taper of each pair of surfaces may be the same, but in other instances it may be desirable to form them slightly differently depending upon the particular operating characteristics of the motor to be controlled.

Valve 41 is normally held in its centered position by springs 68 and 69 so that the intermediate portion of the lands 62 and 63 completelyclose the ports 43 and 45 respectively of the chamber 38. One end of the spring 68 seats against the right-hand end wall of the chamber 38 and its other end seats against and normally urges an annular albutment 70 against a shoulder 71 of the chamber. One end of the second spring 69 seats against the annular abutment 70 and its other end seats against a shoulder 72 of the valve 41 and urges a second shoulder 74 of the valve 41 in engagement with the annular abutment member 78. Valve 41 is provided with a longitudinally extending central passageway 75 opening outwardly through the end thereof having the shoulder 72 and having a first radially extending portion 76 which opens outwardly thereof to communicate with the lefthand end of the valve chamber 38 and a second radially extending passageway portion 77 which opens outwardly of valve 41 intermediate the valve land 63 and shoulder 7 4.

The right-hand ends of the valve chambers 36 and 38 are connected together and to the reservoir 11 by means of a drain passageway 78. The passageway 75 therefore acts to connect the left-hand groove of the spool valves 44) and 41 to the respective right-hand ends of the chambers 36 and 38 whereby each end thereof is connected to the drain passageway and any fluid leaking by the lands 62 and 63, as well as return fluid from the motor 5 and cylinder 6, is returned to the reservoir 11.

The right-hand end of the chamber 36 is connected by a drain passageway 79 to the master valve 32. In the energized position of the master valve 32 a land 80 of the element 52 closes communication between the passageway 79 and a passageway 81 and conduit 82 which lead to a piston chamber 83 below a piston 84 in a traverse gear box shifter 86.

During power operation of the aiming apparatus 1, the piston 84 of the gear box shifter is maintained in its upper position against the force of the return spring 87 by fluid pressure in the chamber 83. In this position the pinion gear 88 disconnects the manually rotat eesassb able gear 90 from the gear train driven by the motor 5. This disconnection of the hand cranking device is desirable to disconnect the no-back construction usually embodied in such a cranking device. Such no-back construction would otherwise prevent movement of the turret by motor 5. In types of tanks such as the M-48, the piston 84 could be used to insert and remove the usual hydraulic motor lock used in this type of tank. The fluid pressure for the chamber 83 is supplied from passageway 35 through a passageway 92, pressure reducing valve 93, and passageway 94 which when the master valve 32 is in its open position is communicatively connected to passageway 81. When valve 32 moves to closed position, communication between passageways 94 and 81 is interrupted by the land 80 and passageway 81 is connected to the reservoir 11 through passageways 79 and 78. This connection relieves the fluid pressure in chamber 83 when the master valve 32 is closed and permits spring 87 to place the gear 88 in mesh with gear 90 whereby rotation of gear 90 by a suitable crank (not shown) is effective to rotate the turret.

The cannon elevating cylinder 6 includes a piston 95 positioned within a cylinder 96. The lower end of the piston 95 is held against vertical movement by a pin (not shown) extending through an eye 97 in its lower end portion. The upper end portion of the cylinder is suitably attached as at 98 to the cannon 91 which is mounted on trunnions 99. The piston is provided with a pair of passageways 100 and 101 opening at their upper ends within the cylinder 96 above and below, respectively, the head portion 102 of the piston 95. The lower end of the elevating piston 95 is enlarged and provided with a pair of vertically extending cylindrical valve chambers 103 and 104. The lower end portions of these chambers are interconnected by means of a lower transversely extending passageway 105, and their upper end portions are interconnected by an upper transversely extending passageway 106. The passageway 105 is in open communication with the passageway 100 and passageway 106 is in open communication with passageway 101. A pair of pressure relief valves 107 and 108 interconnect the passageways 105 and 106 and by-pass fluid there between Whenever the pressure difference therebetween exceeds a desired value, thereby preventing excessive shock to the system when the vehicle is crossing rough terrain.

A spool valve 110 is provided in the valve chamber 103 and is normally held in its shown centered position by means of centering springs 111 and 112. More particularly, one end of the spring 111 is located between the upper end wall of chamber 103 and an annular member 113. The spring 112 similarly is located between the lower end wall. of the chamber and a lower annular member 114. The chamber 103 is provided with a pair of outwardly facing shoulders 115 and 116 which are spaced apart substantially the length of valve 110. These annular members 113 and 114 are urged by their respective springs against the shoulders 115 and 116 respectively and thereby normally maintain the valve 110 centered with the passageways 105 and 106 isolated from the chamber 103. When, however, fluid under pressure is admitted to conduit 60 the fluid moves the valve 110 upwardly against the force of the spring 111. This upward movement moves land 117 upwardly to place the conduit 60 in fluid. flow communication with the lower transverse passageway 105. The upper land 1118 of this valve 110 moves upwardly to a position in which an upper internal passageway 119, separated from a lower internal passageway 120 by land 121, communicatively connects the passageway 106 to the conduit 61 through the annular member 113. In order to insure that the valve 110 will close as a consequence of closure of the valve 41, the land 121 may be arranged to permit a small leakage flow thereby, so that any remaining differential in pressure across the valve 110 may be equalized.

If pressure fluid is admitted to conduit 61, the valve 110 moves downwardly and land 118 permits fluid to flow into passageway 106 from conduit 61 and in this position of valve 110 the passageway communicates with the conduit 60 through passageway 120. Upon the admission of pressure fluid to the conduit 60, the valve will move upwardly admitting pressure fluid through the passageways 105 and 100 to the upper end portion of the cylinder 96. Since the piston 95 is fixedly held, the cylinder 96 will be moved upwardly to tilt the cannon 91 to lower the elevation thereof. As the cylinder 96 moves upwardly, fluid exhausts from the lower end portion of cylinder 96 through the passageways 101 and 106 and passageway 119 of the valve member 110 to the conduit 61.

Conversely, when pressure fluid is admitted to the conduit 61 the valve 110 moves downwardly to open the conduit 61 into the passageway 106 and to connect the passageway 105 through passageway 120 to the conduit 60 to admit fluid to the lower portion of cylinder 96 and to exhaust fluid from the upper portion of the cylinder 96. A similar valve 122 with lands 123, 124 and 125 and internal passageways 126 and 127, normally held in centered position by springs 128 and 129, is located in the valve chamber 104 and cooperates with conduits 130 and 132, similarly as does valve 110 with conduits 60 and 61. As will be subsequently described, conduits 130 and 132 are used for conducting fluid to and from the cylinder 96 when the elevating cylinder 6 is operated manually from the hand operated pump 134.

The manual system for controlling the cylinder 6 includes the above mentioned valve 122, conduits 130 and 132 and a reversible hand pump 134. Fluid for the manual system is derived directly from the reservoir 11 through passageway 136, check valve 138 and passageway 140 which opens into a passageway 142 which connects one of the pump ports 144 with the conduit 130. The pump 134 can be of any bi-directional type which will upon rotation of the hand crank 146 provide the required fluid pressure between its ports 144 and 148. As shown, the pump 134 is of the piston type having a casing 150 enclosing the pistons and swash plate actuated valves. The port 148 is connected by passageway 152 with the conduit 132 while the interior of the casing 150 is connected to passageway 154 which is selectively in communication with the passageways 142 and 152. More specifically, the passageway 154 opens into a central portion of a transversely extending pas sageway 156 opening into the passageways 142 and 152.

A shuttle valve 158 has opposite head portions or lands 159 and 160. The lands are spaced relative to each other and relative to the distance between the out- =lets of passageway 156 into the passageways 142 and 152 so that the lands will always prevent flow between the passageways 142 and 152 but will selectively render the passageway 154 in communication with the one of the passageways 142 and 152 in which the hydraulic pressure is lower.

The passageway 152 is provided with a branch passageway 162 which opens into a manual elevation system accumulator 164 which is similar to but preferably smaller than the accumulator 20. Accumulator 164 acts as a source of supercharging pressure fluid for facilitating the manual operation of cylinder 6. The accumulator 164 is charged from the reservoir 11 by the pump 134 by rotating its crank 146 in a direction to pressurize the right-hand passageway 152. With the cannon 91 located in its extreme downward position against any suitable stop (not shown), the pump 134 will draw fluid from the reservoir 11 through passageways 136, 140 and 142 and the check valve 138 and discharge fluid through port 148. Once the elevating cylinder 6 is driven to the limit of its extension and thus prevented from further depressing the cannon 91, the pumped fluid will be forced through passageway 162 into the accumulator 164.

At this time, the shuttle valve 158 will be in its leftward position, causing the pressure of the interior 166 of the pump casing 150 to be the same as the inlet pressure of the pump. The pump 134 is actuated to charge the accumulator 164 to any desired pressure such as, for example, about 300 pounds p.s.i., for supercharging the manual system. When the pump 134 is released, the fluid pressure equalizes throughout the manual system including the pump 134 and the conduits 130 and 132 which lead to the elevation cylinder. Thereafter, the crank 146 may be rotated in one direction or the other to establish a desired fluid flow through the conduits 130 and 132 to elevate or depress the cannon 91. The accumulator 164 will insure a suflicient amount of supercharging fluid pressure for proper operation of the manual system. Fluid which may escape from this system may be replaced by recharging the accumulator as described above.

The operation of the fluid systems so far described is as follows:

Upon closure of the loaders safety switch 168 and main power switch 169, operation of the motor 2 is placed under control of the pressure switch 26 which thereupon acts to start and stop the motor 2 to maintain the desired pressure in the accumulator 20. Closure of the switches 168 and 169 also energizes the solenoid 34 to place the master valve 32 in its shown open position whereby pressure fluid is supplied to the passageway 35. Fluid under pressure regulated by the pressure controlling valve 93, and passing through master valve 32 fills the chamber 83 of the gear box shifter 86 to uncouple gear 90 from the gear box controlling rotation of the turret.

When it is desired to rotate the turret, the spool valve 40 is longitudinally moved either inwardly or outwardly depending upon the desired direction of rotation which for purposes of description will be outwardly for counterclockwise and inwardly for clockwise rotation. The specific mechanism for controlling the valves 40 and 41 is the valve control box 7 actuated either by the gunners control mechanism 8 or the commanders mechanism 9 as will be described more fully below. Assuming that valve 40 has been moved outwardly (-to the left as viewed in Fig. 1), fluid now flows from the accumulator 20, through passageway 16, master valve 32, port 42, passageway 46, conduit 48, motor 5, conduit 49, passageway 47, port 44 and passageways 77, 75 and 78 to the reservoir 11. As shown, the angle of taper of land portion 65 is substantially the same as that of the land portion 67 and the flow of fluid is regulated at both ports 42 and 44 so that surge of pressure through the motor is prevented. A regulated rate of fluid then flows through the fluid motor 5 which then drives the gear train (not shown) at a regulated speed to rotate the turret in a counterclockwise direction. Return of the valve 40 inwardly to neutral position stops all fluid flow by sealing off the ports 42 and 44.

This stops further rotation of the motor 5 which then is locked in its stopped position by the fluid trapped in the motor fluid system. If, however, an unduly great rotative force were applied to the turret, such as the cannon 91 hitting an obstruction, safety pressure relief valve 172 will permit flow of fluid between the conduits 48 and '49 and thereby permit rotation of the turret without damage to the fluid system and other mechanism. The stem of valve 172 is provided with a slot 174 and a piston 176 in a piston chamber 178. A spring 180 normally holds valve 172 closed. If the pressure within the conduit 49 exceeds a predetermined value, the pressure acting on the end of valve 172 will overcome the force of spring 180 and the valve will open. If the obstruction is such as to increase the pressure in conduit 48, fluid pressure will act on the piston 176 through slot 174 and move the valve 172 to permit flow from conduit 48 to conduit 49.

Traverse circuit keep-full valves 182 and 184 are provided to supercharge the motor circuit, and permit fluid flow from the passageway 81 into passageways 47 and 46 respectively. This improves the response of the motor 5 and keeps it in condition to lock the turret against rotation except when fluid is supplied to motor 5 by the valve 40 or when the master valve 32 is in its de-energized position and the turret is being manually controlled. The valves 182 and 184 comprise spring pressed balls moved toward open position when the pressure in passageway 81 exceeds that in passageways 47 and/or 46 by a predetermined amount.

Movement of the spool valve 41, which is similar in construction to valve 40 and cooperates similarly with the ports 43 and 45, acts to provide a controlled fluid flow through the conduits 60 and 61 to elevate or depress the cannon 91. Movement of the valve 41 outwardly (to the left as viewed in Fig. 1) permits fluid to flow from passageway 35 through port 43 and conduit 60 to move valve 110 upwardly. Fluid then flows from conduit 60 through passageways and 100 into the upper portion of the cylinder 96. This causes cylinder 96 to move upwardly to depress the cannon 91. As the cylinder 96 moves upwardly, fluid is expelled from the lower portion thereof through passageways 101, 106 and 119, conduit 61, passageway 59, port 45 and passageway 78 to the reservoir 11. Return of the valve 41 in an inwardly direction to its normal centered position closes the ports 43 and 45 and locks the elevating cylinder in its adjusted position, with valve 110 returning to its normal centered position by the springs 111 and 112 as the pressure equalizes thereacross either through the cylinder 6 or by the leakage past land 121. Movement of the valve 41 inwardly causes fluid to flow from passageway 35 through conduit 61 to move valve 110 downwardly and therethrough and through passageways 106 and 101 to the lower end portion of cylinder 96 moving the cylinder 96 downwardly to elevate the cannon 91. Fluid from the upper portion of the cylinder 96 flows through passageways 100, 105, and 120, conduit 60, passageway 58, port '43, the passageway within the valve 41, and passageway 78 to the reservoir 11.

The construction by which the spool valves 40 and 41 act to throttle both the inlet and outlet passageways to the fluid powered units, which may be either motor 5 or cylinder 6, is an important part of this invention. When both ports of one of the valves are closed, the power unit associated therewith and its connecting passageways are maintained full of liquid. When the valve is initially moved to a throttling position and the inlet and outlet ports are initially opened for fluid flow therethrough, a full supply pressure is applied to the power unit. Just as soon, however, as the power unit moves and fluid flow starts, a pressure drop appears across both the inlet and outlet ports of the valve. If the powerunit tends to move more rapidly than the position of the valve would justify, there is an immediate build up in pressure across both the inlet and outlet ports with a consequent reduction in pressure drop across the power unit. If, on the other hand, the power unit tends to move less rapidly, then there is a consequent lowering of the pressure drop across each of the ports which results in a greater pressure available for movement of the power unit. Since the liquid lines are always fully charged, any slight tendency of the power unit to vary its rate of movement will immediately result in a compensating change in the pressure drop across the power unit. If only a single valve on the inlet side of the power unit were used, then a slowing down of the power unit would permit a rapid build up of pressure across the power unit and when the unit did finally start to increase its rate of movement it would tend to accelerate to a more rapid rate than was desired since there would to the turret.

m sts ill be no braking fore-eon the outlet of the power unit. This would be particularly true in instances in which, the force required to drive the apparatus powered by the power unit was of avariabl'e nature. Certain of my advantages could be obtained by merely valving only the outlet of the power unit, but in such event the fluid pressure in the power unit would be at the elevated fluid pressure of the source. With certain types of power units this might not be too objectionable.

With types of power units such as fluid motors which are commonly used for rotating tank turrets, certain of the parts would be subject to a difierence in pressure between that of the source and that in its surrounding casing which for obvious reasons is normally maintained at atmospheric pressure. At slow speed operation this unnecessarily great pressure difference across these parts tends to cause them to bind and give a jerky movement By throttling the inlet as well as the outlet pressure to such a fluid motor, the pressure of the admitted fluid is substantially reduced and the tendency ofthe motor to operate jerkily is greatly reduced if not completely eliminated without, at the same time, resulting in a tendency for the motor to change in speed as a consequence of variations in power required to rotate the turret or other mechanism driven thereby.

With the piston cylinder type of power unit, the double throttling prevents jump which might result if full pressure differential were suddenly admitted across the piston due 'to the compressibility of the fluid therein.

When manual operation of the turret and cannon elevating cylinder is desired, switch 169 is opened to deener'gize the solenoid 34 whereby spring 54 moves the master valve 32 to closed position. Movement of valve 32 to off position disconnects the passageway 81 from the pressure supplying passageway 94 and connects passageway 81 to drain passageways 78 and 79. Piston 84 then moves downwardly under the force of spring 87 to connect the gear 90 with the gear train (not shown) for revolving the tank turret. Closing of the master valve 32 also disconnects passageway 35 from the main supply passageway 16 leading to the accumulator 20 and interconnects the motor circuit passageways 46 and 47. With the gear 90 so connected manual rotation thereof by a crank (not shown) acts to revolve the turret and cannon 91. Elevating and depressing of the cannon 91 is accomplished by manually rotating the handwheel 146 of the hand operated pump 134 in one direction or the other to pump fluid into one or the other of the conduits 130 and 132 depending on the direction of pump rotation. Fluid so pumped then acts through the valve 122 in a similar manner to that described in connection with power operation through conduits 60 and 61, and valve 110. The shuttle valve 158 will shuttle to a position in which the interior of the pump housing 150 is'connected to the inlet side of the pump 134 to always maintain the pressure in the housing interior the same as that of the inlet pressure to the pump.

The valve block 4 is provided with an additional piston chamber 186 having a piston 188 which actuates the valve control box 7 to permit the tank commander to assume control of the apparatus 1. Flow of fluid for controlling the piston 188 is under control of a valve 190 actuated by a solenoid 192. Normally'the solenoid 192 is maintained de-energized thereby'permitting' spring 194 to hold this valve in the illustrated position in which a passageway 195 opening into the end portion of the chamber 186 behind the piston 188 is opened to the drain passageway 78. Upon energization of the solenoid 192, the valve 190 is moved to the left, as viewed in Fig. 1, against the force of the spring 194 to seal off the connection of the passageway 195 to the passageway 78 and place it in communication with a branch passageway 196 of the pressure fluid supplying passageway 35. The energization of the solenoid 192 is under control of a normally open switch 198 available for operation by the tank (commander.

=In Fig. 4, in which like parts to Fig. v1 are identified by the same numerals, there is shown a somewhat modified form of a manually operated :cannon elevating system in which fluid for charging the manual system accumulator 164 and the fluid for operating the piston 188 are normally supplied from the pressure reducing valve 93 so that the accumulator 164 is continually maintained charged from the main hydraulic fluid system and the operating force on the piston 188 is reduced. In this instance the passageway 196 is made a branch of passageway 94 instead of passageway 35. Passageway 196 then connects the valve 93 through a manually operated power charging cut-off safety valve 202 to the passageway 154 which in this form is in open communication through passageway 162 with accumulator 164. The valve 202 is normally maintained in its shown position in which the spring pressed ball valve 204 thereof acts as a check valve to permit fluid flow into the manual system but prevents flow therefrom. Valve 202 may however be turned so that the stem thereof positively holds the ball 204, against its seat to isolatethe manual system.

In the event that it is desired to manually charge the manual system, a hand pump 206 is provided. Operation of pump 206 is by means of a manually operated lever 208. The pump 206 is connected through check valve 138 and passageway 136 to the reservoir 11. When operated, the hand'pump 206 withdraws liquid from the reservoir 11 and pumps it through check valve 210 into the passageway 154 and passageway 162 to accumulator 164. The passageway 154 is connected through a pressure relief valve 212 to the drain passageway 78. This pressure relief valve 212 controls the maximum pressure which is permitted within the housing of the manual actuating pump 134.

In this form the shuttle valve158 has been replaced by a pair of pressure actuated valves 158a and 158b which serve as check valves to permit charging of the manual fluid systems. When the pump 134 is operated, the pressure in the passageway 142 or 152 may be reduced below that in the accumulator 164. If the manual system is completely filled it would be undesirable to add further fluid since upon discontinuance of the operating of the pump 134 pressure in the system might be greater than the desired pressure. Valves 158a and 158b are therefore provided with pressure sensitive plungers which are respectively sensitive to the difference in pressure between the passageways 142 and 152. When the pressure in passageway 152 exceeds that in 142 by a predetermined amount, the piston associated with valve 158]) is moved to the right to hold the ball valve associated therewith tightly against its port to prevent a flow of liquid from the passageway 154 into the passageway 142. Conversely, when the pressure in passageway 142 exceeds that in passageway 152 by a predetermined amount, the piston associated with the valve 158a is moved to the right to hold its respective ball valve tightly against its port to prevent liquid to flow from passageway 154 into passageway 152.

Fig. 3 diagrammatically shows the commanders override control 9 attached to the inner wall of the tank turret 212 and operatively connected by means of a pair of rods 214 and 216 with the arms 218 and 220 for rotation of the rotatable rods 219 and 221 respectively pivoted for oscillating movement in the valve controlling box 7.

The valve control box 7 as shown in Fig. 5 houses a pair of pivoted blades 224. and 226 which connect the elevating and traversing valves 41 and 40 respectively with either the gunners control 8 or the commanders control 9. The blades .224 and. 226 are pivoted on opposite ends of a stub shaft 228 which in turn is mounted at opposite ends within slots 225 of guide plates 227 11 and 229 carried by the box 7. A swivel arm 232 is provided with a slot 230 through which the shaft 228 extends. As shown, the swivel arm 232 is normally urged by a compression spring 234 into its clockwise position in which the blades 224 and 226 of the valve control box are actuatable by the gunners control mechanism 8. The swivel arm 232 is pivotally mounted on a stub shaft 242 which is held at its end portions within suitable bosses carried by the top and bottom walls 240 and 244 of the box 7. When the solenoid 192 is energized, the fluid pressure operated piston 188, which is engageable with the arm 232, will rotate the arm 232 counterclockwise against the force of spring 234 from its position shown in Fig. to the position shown in Fig. 6 in which the blades 224 and 226 will be under control of the commanders control 9 and entirely disconnected from the gunners control 8.

The blades 224 and 226 are of similar construction, and are each provided with'a slot 250 and 252 opening outwardly through opposite end surfaces. If desired, each of these slots may have a clearance hole 254 in their-inner end portion for convenience of manufacture and to relieve stresses. The end walls of the blades are provided with tapering walls 256 tapering inwardly toward the slots 250 and 252 for a purpose which will be made clear below.

The blades 224 and 226 and the slots 252 are preferably of such length that the roller abutments 258 and the roller 260 carried by the am 262 and the roller 261 of the arm 263 are located within the respective slots 252, and the rollers 264 and 265 of the arms 266 and 267 mounted on the shafts 219 and 221 are without the slots 250. When the swivel arm 232 is in its counterclockwise position as shown in Fig. 6, the rollers 260 and 261 are without the slots 252 while the rollers 264 and 265 are within the slots 250. It will therefore now be appreciated that the rotative positions of the blades 224 and 226 continually control the positioning of the valves 40 and 41 but that the blades 224 and 226 will be controlled by the arms 262 and 263 at one rotative position of swivel arm 232 and by the arms 266 and 267 at a second rotative position of swivel arm 232.

The arms 262 and 263 are moved by the gunners control 8 while the movement of the arms 266 and 267 are under control of the commanders control 9. More specifically, the arm 262 is pivotally secured to the box 7 on a fixed pin 268 and is provided with a second roller 269 which is received within a helical cam slot 270 carried by a hollow cylindrical sleeve 271. The sleeve 271 is held against movement longitudinally but is journaled for rotation in bearings 272. One end of the sleeve extends outwardly of the box 7 and has a hollow casing 273 secured thereto. A hollow ended shaft 274 extends transversely of the axis of rotation of the sleeve 271 and is suitably journaled in bearings 275 for rotation of the shaft 274 about its longitudinal axis. Gunners handles 276 are secured to opposite ends of the shaft 274 and provide means for rotating the sleeve 271 and the shaft 274. The two handles 276 are mirror copies of each other and each may be provided with manually operable control switches 277 for firing of the cannon and/ or other guns by means not shown. Rotation of the sleeve 271 causes the roller 269 to be moved longitudinally of the 'sleeve 271 and the arm 262 is rocked about its pivot pin 268' to pivot the blades 226 when the swivel arm 232 is in a position as shown in Fig. 5. Pivoting of the blade 226 moves the traversing spool valve 40 to control the admission of fluid to the traversing motor 5 and the rotation of the turret 212. e

A crank arm 278 is secured to a mid-section of the shaft 274 and is journaled to one end of a rod 279 which extends upwardly through the hollow interior of the casing 273 and sleeve 271. The other end of the rod 279 is journaled to a pin 280 carried by the arm 263 and which pin 280 may also serve as the support for the roller 261. With this arrangement rotation of the shaft 274 acts to pivot the arm 263 to pivot the blade 224 to control the position of the elevating spool valve 41. The rod 279 is journaled as at 279a intermediate its ends which penmits the outer end of the rod 279 to rotate with the sleeve 271.

The commanders control 9 is quite similar in construction to the gunners control in that it comprises a cylindrical member 271a held against axial movement but journaled for rotational movement on bearings 275a mounted in a housing 282. The member 271a is provided with a diagonally extending peripheral cam slot 27011 which receives a roller 269a carried by an arm 263a pivotally mounted on the housing 282 similarly to the way in which arm 263 is mounted in the gunners control 8. A pin 280a carried by the arm 263a serves as the pivot for roller 269a and a bearing 284 which is secured to one end of the shaft 214 which connects with the arm 218 of the valve control box 7. A commanders handle 276a is pivotally mounted on a bearing 286 carried on a bracket 288 which inrturn is carried by the member 271a externally of the housing 282. The shaft 216 which has one end pivotally secured to the arm 220 extends through a longitudinally extending central aperture 290 of the cylindrical member 271a and has its other end pivotally secured to the commanders handle 276a as at .292. In addition to the cannon firing switch 277a, the handle 276a is provided with a switch 198 by which the commander is enabled to control the energization of the solenoid 192 and consequently the operation of the valve 190. When the commander closeshis hand about the handle 276a and actuates the switch 198, the solenoid 192 is energized to actuate the valve to cause pressure fluid to force the piston 188 outwardly to rotate the swivel arm 232 and move the blades 224 and 226 into the position thereof shown in Fig. 6 so that movement thereof and of the valves 40 and 41 is under control of the commanders control 9. Having thusly assumed control, the commander may now rotate his handle 276a about the longitudinal axis of the member 271a to rotate the member 271a to control the traversingcontrolling valve 40, and may pivot the handle 276a in a vertical sense to control the elevating controlling valve 41 independently of any movement of the gunners control 8 since at this time the blades 224 and 226 are free of the rollers 2601 and 261.

The commanders control 9 is maintained in fixed position with respect to the valve control box 7 by suitable means and which may if desired include an angle bar 296. Lateral rotation of the handle 276a rotates the cylindrical member 271a causing the roller 269a to move longitudinally of the member 271a and to longitudinally move the shaft 214 which through the arm 218 pivots the shaft 219 of the valve control box 7. Pivoting of the shaft 219 pivots the arm 266 to rock the blade 226 to control the traversing valve 40. Likewise, fore and aft rotation of the handle 276a will move the shaft 216 which through arm 220 pivots the shaft 221. Pivoting 'of shaft 221 pivots the arm 267 to rock the blade 224 to, control the elevating valve 41.

While illustrative embodiments of the invention have been shown, they should not be understood as limiting the scope of the invention but merely as illustrating the best presently known embodiment of the invention in accordance with the patent statutes.

What is claimed and is desired to be secured by United States Letters Patent is as follows:

1. A hydraulic control system for interconnection between a pressure fluid source and a bi-directional fiuid actuatable motor in apparatus of the type wherein a load is arranged to be driven alternatively by the motor and by a manually operatable device, said system comprising a four-way valve having first and second ports for connection to a pressure fluid source and to a drain, respectively, and third and fourth ports for connection to the motor, a master valve having a closable passage connected in series flow between said first port and the source and two other passages connected in series flow between said third and fourth ports, respectively, and the motor, said master valve being selectively movable between an On position and an Off position and being effective when in its On position to open all of said passages as separate fluid flow paths, said master valve being arranged when in its Off position to close said closable passage thereby cutting off pressure fluid from said control valve, and to open communication between said two other passages, a manually operatable device for driving the load, a releasable coupling device for coupling and decoupling said manually operatable device to and from the load, a fluid pressure actuatable device for actuating said coupling and decoupling device, and means defining an auxiliary hydraulic passage for energizing said fluid actuatable device, said master valve also being connected in and including valve means for admitting pressure fluid into said auxiliary passage from the source when said master valve is in its On position and for connecting said auxiliary passage to the drain when said master valve is in its 01f position.

2. A hydraulic control system for interconnection between a pressure fluid source and a bi-directional fluid actuatable motor comprising a four-way valve having first and second ports for connection to a pressure fluid source and to a drain, respectively, and third and fourth ports for connection to the motor, a master valve having a closable passage connected in series flow between said first port and the source and two other passages connected in series flow between said third and fourth ports, respectively, and the motor, said master valve being selectively movable between an On position and an 01f position and being eifective when in its On position to open all of said passages as separate fluid flow paths, said master valve being arranged when in its Off position to close said closable passage thereby cutting off pressure fluid from said control valve, and to open communication between said two other passages, means defining an auxiliary hydraulic passage, check valve means connecting said auxiliary passage with said two other passages for supercharging said two other passages, means for pressurizing said auxiliary passage at a pressure lower than the pressure of said source, said master valve being arranged to connect said auxiliary passage to the fluid source when said master valve is in its On position and to connect said auxiliary passage to the drain when said master valve is in its Otf position.

3. A hydraulic control valve assembly for interconnection between a pressure fluid source and a bi-directional fluid actuatable motor comprising a compact valve body having a master valve, a control valve, and a pressure reducing valve therein and passageways interconnecting said valves with each other and with external ports, said control valve being a four-way valve having first and second ports for connection to a pressure fluid source and to a drain, respectively, and third and fourth ports for connection to the motor, said master valve being a spool valve having a first passage connected in series flow between said first port of the control valve and the source and second and third passages connected in series flo'w between said third and fourth ports, respectively, and the motor, said pressure reducing valve having an inlet port connected to said first passage on the opposite side of said master valve from the source and having an outlet port for connection to said second and third passages for supercharging them at a pressure below the full working pressure at the inlet of saidmaster valve, said master valve having a fourth passage in series flow between said reducing valve outlet port and said second and third passages, check valve means between said fourth passage and said second and third passages for permitting fluid flow from said fourth passage to said second and third passages and blocking fluid flow in the back direction from said second and third passages to said fourth passage, said master valve being selectively actuatable between an On position and an Ofi position and being operative when in its On position to open said first, second, third and fourth passages as separate fluid paths, said master valve being operative when in its Off position to close said first and fourth passages and to interconnect said second and third passages.

References Cited in the file of this patent UNITED STATES PATENTS 807,865 Prescott Dec. 19, 1905 1,269,338 Tourreil June 11, 1918 1,387,678 Anderson Aug. 16, 1921 1,468,114 Kendrick Sept. 18, 1923 1,974,134 Douglas Sept. 18, 1934 2,017,115 Zouck Oct. 15, 1935 2,077,150 McWhirter et al. Apr. 13, 1937 2,153,056 West Apr. 4, 1939 2,179,179 Fischel et al. Nov. 7, 1939 2,388,010 Pohl Oct. 30, 1945 2,403,519 Gardiner July 9, 1946 2,434,689 Ewart Jan. 20, 1948 2,467,508 Trautman Apr. 19, 1949 2,481,853 Lynn Sept. 13, 1949 2,516,449 Coates July 25, 1950 2,550,671 Chinn May 1, 1951 2,570,622 Willis Oct. 9, 1951 2,593,412 Chad-wick et a1 Apr. 22, 1952 2,596,242 Hill May 13, 1952 2,615,430 Fletcher et al. Oct. 28, 1952 2,631,571 Parker Mar. 17, 1953 2,680,491 Davidson June 8, 1954 FOREIGN PATENTS 401,937 France Aug. 10, 1909 986,906 France Apr. 11, 1951 360,458 Great Britain Nov. 2, 1931 

